System including a computer and a fuel cell that communicates with the computer and supplies power to the computer

ABSTRACT

A computer system of this invention includes a power input terminal which is provided outside a personal computer, and an external fuel cell assembly connected to the power input terminal. Hence, a computer system in which water produced from the fuel cell assembly is prevented from entering the computer can be provided. A personal computer for which an operation mode for deriving the personal computer by a fuel cell assembly is prepared to prevent any trouble due to user&#39;s misunderstanding can be provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 09/905,971, filed Jul. 17,2001, now U.S. Pat. No. 6,910,138 which is incorporated herein byreference.

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2000-216271, filed Jul. 17,2000, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relate to a computer system using a fuel cellassembly as a power supply and, more particularly, to a personalcomputer using a fuel cell assembly of type which directly oxidizesmethanol.

2. Description of the Related Art

Various personal computers using a fuel cell assembly have been devised.In a conventional personal computer using a fuel cell assembly, the fuelcell assembly is set in the personal computer main body.

Such a personal computer is disclosed in, e.g., Jpn. Pat. Appln. KOKAIPublication No. 9-213359. The fuel cell assembly disclosed in Jpn. Pat.Appln. KOKAI Publication No. 9-213359 uses a hydrogen-absorbing metal.

A fuel cell assembly inevitably produces water. This water is normallyvaporized using heat generated in the computer. In some cases, however,the vapor liquefies in the housing of the personal computer undervarious environmental conditions. A design for preventing the water fromentering the personal computer conflicts required conditions for heatdissipation, ventilation, and the like.

That is, in the conventional personal computer, the fuel cell assemblyis set in the personal computer, and when water produced from the fuelcell assembly enters the personal computer, the personal computermalfunctions.

In addition to a fuel cell assembly with a hydrogen storage unit using ahydrogen-absorbing alloy, a DMFC (Direct Method Fuel Cell) has beendevised. Such a DMFC is disclosed in, e.g., Japanese Patent ApplicationNo. 10-278759 filed by the present applicant. The DMFC does not requireso-called auxiliary equipment for pumping fuel and hence has no movablemechanical portion. For this reason, the DMFC is readily made compactand lightweight and therefore is suitable as a power supply of anotebook personal computer.

If, however, a DMFC is designed not to have a stacked cell structure soas to manufacture the cell at a low cost, air supplied to the cellrelies on diffusion and convection. As a consequence, to supply powerrequired for a current notebook PC, the DMFC has an excessively largearea. Even if the performance of a DMFC improves to, for example, 45mW/cm², the cell needs to have an area of 1,000 cm² to supply 45 W.

The biggest merit in using a fuel cell assembly for a portable apparatusis that the apparatus can be used substantially unlimited time period inthe AC power less embodiment, as long as a fuel is carried. When thefuel cell assembly is used, it is required to restrict a performance andfunction of the personal computer.

While being out as long as a fuel is carried. However, the power thatcan be extracted from the fuel cell assembly is limited. If a highpriority is to be given to the long-term use of a personal computer evenat the expense of performance, the personal computer needs to beoperated with a great restriction on power consumption. However, presentnotebook PCs are not designed to operate on the power that can beextracted from a fuel cell assembly.

Many current notebook personal computers are designed assuming, as amain power supply, an Li ion cell charged using a dedicated AC adapter.In this case, for the viewpoint of efficiency and the like, it issupposed to be optimum to design a secondary cell with a terminalvoltage of about 10V by connecting three cells in series in a batterypack.

The cell output voltage of a fuel cell assembly is about 0.5V inoperation. A fuel cell assembly having a number of cells stacked (thistype is hard to manufacture and be inexpensive) is generally designed toobtain such an output voltage, though it is expensive and difficult touse.

For cost reduction, a personal computer operable by a low-level voltage,which can easily be obtained by segmenting a grid into a plurality ofportions in an integrated fuel cell assembly and connecting thoseportions in series, is necessary.

However, with the low power obtained by such a fuel cell assembly, theconventional computer system cannot normally operate when apower-consuming application is executed.

BRIEF SUMMARY OF THE INVENTION

The present invention has been made in consideration of the abovesituation, and has as its object to provide a computer system in whichwater produced from a fuel cell assembly is prevented from entering thecomputer.

It is another object of the present invention to provide a computersystem which can be normally operated even by a low output obtained froma fuel cell assembly.

In order to achieve the above objects, according to the first aspect ofthe present invention, there is provided a computer system comprising apower input terminal which is provided outside a personal computer, andan external fuel cell assembly connected to the power input terminal.

According to this aspect, by externally connecting the fuel cellassembly to the personal computer, water produced from the fuel cellassembly can be prevented from entering the personal computer to resultin malfunction of the personal computer.

According to the second aspect of the present invention, there isprovided a personal computer comprising means for determining whether apower supply is a fuel cell assembly on the basis of a received powersupply output, means for, when it is determined that the power supply isthe fuel cell assembly, switching an operation mode to a fuel cellassembly mode in which the fuel cell assembly is used as the powersupply.

According to this aspect, when it is determined that the power supply isthe fuel cell assembly, the operation mode of the personal computer isswitched to the fuel cell assembly mode in which the fuel cell assemblyis used as the power supply. Hence, even when the output level of thefuel cell assembly is low, the personal computer can normally operate.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently embodiments of theinvention, and together with the general description given above and thedetailed description of the embodiments given below, serve to explainthe principles of the invention.

FIG. 1 is a view showing a notebook personal computer system accordingto the first embodiment of the present invention;

FIG. 2 is a block diagram showing the arrangement of the notebookpersonal computer;

FIG. 3 is a flow chart for explaining the operation of the power supplymicrocomputer of the notebook personal computer;

FIG. 4 is a flow chart for explaining the first example of the fuel cellassembly mode;

FIG. 5 is a flow chart for explaining the second example of the fuelcell assembly mode;

FIG. 6 is a flow chart for explaining the third example of the fuel cellassembly mode;

FIG. 7 is a block diagram showing the arrangement of a notebook personalcomputer according to the second embodiment of the present invention;

FIG. 8 is a flow chart for explaining the operation of the power supplymicrocomputer;

FIG. 9 is a chart for explaining mode switching;

FIG. 10 is a view showing the interface between the fuel cell assemblyand the personal computer;

FIG. 11 is a graph showing the output characteristics of the fuel cellassembly when it is assumed that the personal computer is powered onafter the output voltage of the fuel cell assembly sufficiently rises;

FIG. 12 is a circuit diagram showing the power supply section of thenotebook personal computer of this embodiment;

FIG. 13 is a graph showing the output characteristics of the fuel cellassembly of the notebook personal computer of this embodiment; and

FIG. 14 is a circuit diagram showing another example of the power supplysection of the notebook personal computer of this embodiment.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the present invention will be described below withreference to the accompanying drawing.

<First Embodiment>

FIG. 1 is a view showing a notebook personal computer system accordingto the first embodiment of the present invention.

Referring to FIG. 1, reference numeral 1 denotes a notebook personalcomputer; 2, a fuel cell assembly; 3, a support of the fuel cellassembly 2; and 4, a power supply line for supplying the power from thefuel cell assembly 2 to the notebook personal computer 1.

As shown in FIG. 1, the fuel cell assembly 2 is externally connected tothe notebook personal computer 1 through the power supply line 4. Withthis arrangement, the user can process water as needed in accordancewith the environmental conditions for use of the notebook personalcomputer 1. In addition, since the notebook personal computer 1 need nospecial measure against water the notebook personal computer 1 itselfcan be prevented from becoming expensive.

The power supply of the notebook personal computer 1 is not limited tothe fuel cell assembly 2. The notebook personal computer 1 can have alarge power supply capacity by an internal Li cell and receive powerfrom an AC adapter 5.

In this case, the high-speed/high-level operation using power of severalten W is possible as ever. On the other hand, when the fuel cellassembly 2 is used, the notebook personal computer 1 operates in adedicated fuel cell assembly mode capable of executing only applicationprograms other than some especially power-consuming application programsby a method to be described below.

FIG. 2 is a block diagram showing the arrangement of the notebookpersonal computer. The same reference numerals as in FIG. 1 denote thesame parts in FIG. 2, and a detailed description thereof will beomitted.

As shown in FIG. 2, either the fuel cell assembly 2 or AC adapter 5 canbe connected to a power input connector 10 of the notebook personalcomputer 1. The power input from the power input connector 10 isconverted into a voltage appropriate to each part of the notebookpersonal computer 1 by a power supply section 11 and supplied to eachpart of the notebook personal computer 1.

The power supply section 11 charges a battery pack 12 or receives powerfrom the battery pack 12.

One of the power supply destinations of the power supply section 11 is amain board 13. The main board 13 has a CPU 14. As examples of peripheraldevices connected to the main board 13, a modem 15 and DVDplayer/recorder 16 are illustrated in FIG. 2.

The CPU 14 controls the entire notebook personal computer 1. The modem15 communicates with another computer through a communication line. TheDVD player/recorder 16 plays back sound and image recorded on a DVD orrecords sound and image on a DVD.

The power supply section 11 incorporates a DC/DC converter, power supplymicrocomputer, and cell charge/discharge control IC as ever. Even whenthe notebook personal computer 1 is kept OFF, the power supplymicrocomputer is operating by receiving low power so as to monitor suchan event that the power switch of the notebook personal computer 1 isturned on, or power is supplied to the power input connector 10, asever.

One of characteristic features of the notebook personal computer of thisembodiment is the operation of the power supply microcomputer of thepower supply section 11.

As a characteristic feature of the operation of the power supplymicrocomputer of the notebook personal computer according to thisembodiment, after the power input start event, the input power supplyvoltage is monitored, and the subsequent operation mode of the notebookpersonal computer is determined in accordance with the power supplyvoltage.

The operation of the power supply microcomputer of the notebook personalcomputer according to this embodiment will be described below withreference to the flow chart shown in FIG. 3.

First, the power supply microcomputer determines whether the AC adapteris connected (S1). If YES in step S1, a normal mode for executingconventional operation is set (S2).

If NO in step S1, it is determined whether the fuel cell assembly isconnected (S3). If YES in step S3, the mode shifts to a fuel cellassembly mode (S4).

If NO in step S3, the flow returns to processing in step S1. Whether theAC adapter is connected or whether the fuel cell assembly is connectedis determined on the basis of the input power supply voltage.

That is, when the AC adapter is connected, a power of about 15V is inputas ever. When the fuel cell assembly 2 is connected, a power of onlyseveral V (about 2V as a typical value in operation) is input.

For the former case, the power supply microcomputer sets the normal modefor executing conventional operation. For the latter case, the powersupply microcomputer sets the fuel cell assembly mode. Since theoperation mode is automatically set in accordance with the type of powersupply, any mode setting error by user's operation error can beprevented.

When neither power supplies are connected at the time of activation, theinternal cell is used as the main power supply. This case is slightlycomplex and will be described later in the second embodiment.

The fuel cell assembly mode will be described next in detail.

In the fuel cell assembly mode, the power consumption of the notebookpersonal computer 1 in operation is reduced such that the notebookpersonal computer 1 can operate on the basis of the power supplied fromthe fuel cell assembly 2.

Several methods of reducing power consumption are available. Typicalexamples will be described. Any other method may be used as far as itcan reduce power consumption, or some of the methods to be describedbelow may be combined.

In the first example, when the fuel cell assembly mode is set, the CPUis set in a low power consumption mode (S11), as shown in FIG. 4.Operating the power supply section 11 in the low power consumption modeis a well-known technique, and a detailed description thereof will beomitted here. In this fuel cell assembly mode, since the powerconsumption must be largely reduced as compared to the normal mode, thelow power consumption mode is set in the following way.

Recent CPUs are designed with an emphasis mainly placed on powerconsumption reduction in high-speed operation, so the power supplyvoltage of the core in the CPU chip is made as low as possible.

This increases the leakage current of the transistor. In the fuel cellassembly mode wherein the clock speed is considerably reduced, the powersupply voltage of the core is made slightly higher than that in thenormal mode. Hence, the power consumption can be reduced.Conventionally, the power consumption is reduced by dropping the powersupply voltage of the core.

The CPU architecture also preferably has the low power consumption mode.For example, to increase the degree of parallel processing, a recent CPUobtains a result as if a plurality of instructions designated for serialexecution on the program were executed in parallel and the results wereserially output without any inconsistency. In the fuel cell assemblymode, the power consumption is preferably reduced by a design for simplyserially executing commands without supplying the power to a circuit forsuch parallel processing.

In the second example, applications, which cannot be executed in thefuel cell assembly mode or are inappropriate to execute in the fuel cellassembly mode, are not executed.

More specifically, as shown in FIG. 5, the user designates in advanceapplications which cannot be executed in the fuel cell assembly mode orare inappropriate to execute in the fuel cell assembly mode (S12).

In this case, the user designates the applications in advance. However,the applications may be automatically detected by software or designatedin advance at the time of shipment from a factory. The designatedapplications are disabled to inhibit the start (S13).

In this embodiment, traditional office applications (e.g., WORDavailable from Microsoft) and Internet accesses using the modem 15 canoperate (moving image or music application cannot operate, as describedabove). These applications can be practically executed even by a CPUwith considerably low performance and are also determined asapplications whose needs for long-time use outdoor are high.

In the third example, some peripheral devices are not activated.

More specifically, as shown in FIG. 6, some peripheral devices aredisabled (S21). In this embodiment, the DVD player/recorder 16 is notactivated in the fuel cell assembly mode. This is because the DVDplayer/recorder 16 itself requires high power consumption, and a movingimage as a main application that uses the DVD player/recorder 16requires full use of CPU performance and therefore real-time processingcannot be executed by the CPU in the low power consumption mode.

In the fuel cell assembly mode, the battery pack 12 is not charged ordischarged (is not used as a power supply). This is because, in the fuelcell assembly mode, the battery pack 12 is unreliable, and the user mustproperly understand this point. As another reason, inefficient operationof charging the cell by the low voltage of the fuel cell assembly mustbe prevented.

Switching between the fuel cell assembly mode and the normal mode isdone only when the notebook personal computer is kept OFF. Thisfacilitates switching to the low power consumption mode at the CPUarchitecture level and is also important in preventing operation errorby the user.

That is, connection of the fuel cell assembly to the notebook personalcomputer that is operating in the normal mode is inhibited. In thisembodiment, a warning message is displayed in the window, and theoperation in the normal mode is continued. With this arrangement, thefuel cell assembly mode can be clearly interpreted, and discrepancybetween the user's expectation and the operation of the notebookpersonal computer 1 can be prevented.

<Second Embodiment>

The second embodiment of the present invention will be described next.

FIG. 7 is a block diagram showing the arrangement of a notebook personalcomputer according to the second embodiment of the present invention.The same reference numerals as in FIG. 2 denote the same parts in FIG.7, and a detailed description thereof will be omitted. Only differentparts will be described here.

As a characteristic feature of this embodiment, a power input connector17 dedicated to the fuel cell assembly and an electric double-layeredcapacitor 18 are added.

A power input connector 10 of a notebook personal computer 1 isconnected to an AC adapter 5. The notebook personal computer 1 has thepower input connector 17 dedicated to the fuel cell assembly and isconnected to a fuel cell assembly 2.

Both the AC adapter 5 and fuel cell assembly 2 are connected to a powersupply section 11. The power is converted into a voltage appropriate toeach part of the notebook personal computer 1 by the power supplysection 11 and supplied to each part of the notebook personal computer1.

The power supply section 11 is connected to a battery pack 12 so as tobe able to change the battery pack 12 or receive power from the batterypack 12 and supply the power to each part of the notebook personalcomputer 1 as ever, as described above.

One of the power supply destinations of the power supply section 11 is amain board 13 of the notebook personal computer 1. The main board 13 hasa CPU 14. As examples of peripheral devices connected to the main board13, a modem 15, DVD player/recorder 16, and hard disk drive 19 areillustrated in FIG. 7.

The operation of the power supply section in receiving power from the ACadapter 5 or receiving power from the battery pack is basically the sameas the conventional operation. The power supply section 11 incorporatesa DC/DC converter, power supply microcomputer, and cell charge/dischargecontrol IC as ever. Operation performed when the power is supplied fromthe fuel cell assembly 2 is largely different from the conventionaloperation.

That is, the power supply voltage input from the AC adapter is about 15Vas a typical value. For the fuel cell assembly of this embodiment, apower of only several V (about 2V as a typical value in operation) isinput.

Hence, the dedicated connector 17 is used to connect the fuel cellassembly, and a dedicated DC/DC converter is prepared. The power supplymicrocomputer operates while clearly distinguishing between a normalmode for the conventional operation and a fuel cell assembly modewherein the power is supplied from the fuel cell assembly.

While the notebook personal computer 1 is kept OFF, the power supplymicrocomputer identifies which power supply terminal starts power supplyand automatically sets the operation mode. Hence, any mode setting errorby user's operation error can be prevented.

More specifically, as shown in FIG. 8, first, it is determined whetherpower is supplied from the power input connector 10 (S25). If YES instep S25, the mode shifts to the normal mode (S26).

If NO in step S25, it is determined whether the power is supplied fromthe power input connector 17 dedicated to the fuel cell assembly (S27).

If YES in step S27, the mode shifts to the fuel cell assembly mode(S28). If NO in step S27, the flow returns to processing in step S25.

Detailed processing including a case wherein the internal cell is usedas a main power supply will be described later with reference to FIG. 9.The fuel cell assembly mode has been described in the first embodiment,and a repetitive description thereof will be omitted.

Switching between the fuel cell assembly mode and the normal mode isdone only when the notebook personal computer 1 is kept OFF. Thisfacilitates switching to the low power consumption mode at the CPUarchitecture level and is also important in preventing operation errorby the user.

That is, connection of the fuel cell assembly to the notebook personalcomputer that is operating in the normal mode is inhibited. In thisembodiment, when the fuel cell assembly is connected to the notebookpersonal computer that is operating in the normal mode, a warningmessage is displayed in the window, and the operation in the normal modeis continued.

With this arrangement, the fuel cell assembly mode can be clearlyinterpreted, and discrepancy between the user's expectation and theoperation of the notebook personal computer 1 can be prevented.

FIG. 9 is a chart for explaining mode switching of the notebook personalcomputer according to this embodiment. More specifically, this isimplemented as the firmware of the power supply microcomputer in thisembodiment.

A state 40 is the initial state. The overall power supply control of theconventional notebook personal computer is indicated by a frame 44. Inthis case, the power ON sequence in a state 41, the operation sequencein a state 42, and the power OFF sequence in a state 43 are shown.

The state 40 is the conventional OFF state. Each processing sequencestarts in accordance with an event “power SW is turned on”, “AC adapteris connected”, “resume condition is satisfied”, or “Wake On LANcondition is satisfied”.

A series of processes executed when the power switch is turned on areindicated as the states 41 to 43.

The state 40 is the only neutral state in which transit between the fuelcell assembly mode and the normal mode is possible.

When the fuel cell assembly (FC) is connected in this state, the statetransits to a fuel cell assembly mode OFF state 45. When the powerswitch is turned on, the notebook personal computer 1 is activated inthe fuel cell assembly mode.

However, unlike the normal mode by Li cell drive, before the power ONsequence of the notebook personal computer 1 starts, a sequence 46 foractivating the fuel cell assembly is executed.

The manner the fuel cell assembly is activated largely changes dependingon the design of the fuel cell assembly unit. At the start of thissequence, the fuel cell assembly unit is identified.

In this embodiment, the power input connector 17 for the fuel cellassembly has connection for I²C communication, unlike the normalconnector 10 for the AC adapter, as shown in FIG. 10.

CLI2C and DAI2C are clock and data lines for the I²C communication. Forthis communication, any other scheme except that for the I²Ccommunication can be used as long as the required number of signal linesis small.

Basically, only an activation command need be sent from the power supplymicrocomputer of the notebook personal computer 1 to the fuel cellassembly through the I²C communication line shown in FIG. 13 as long asthe fuel cell assembly unit has various auxiliary functions.

In this case, the fuel cell assembly unit autonomously increases thefuel cell assembly temperature and connects an internal dummy load tothe fuel cell assembly to increase the output of the fuel cell assemblyto a predetermined value. This is because the load response of a fuelcell assembly is generally very slow.

If the load largely varies, a time of about 1 sec may be required untilthe current stabilizes. hence, when the notebook personal computer 1 isto be directly activated using the fuel cell assembly in the no loadstate, no sufficient power is supplied.

For a fuel cell assembly unit of inexpensive type with only basicfunctions, when the power switch ON event occurs in the fuel cellassembly mode, the power supply microcomputer connects the output of thefuel cell assembly to the electric double-layered capacitor 18 to setthe fuel cell assembly in the full load state, and starts the power ONsequence after checking that the output of the fuel cell assemblyincreases to a predetermined value or more.

Depending on the type of fuel cell assembly and environmentalconditions, the cell may have to be preheated by reversely feeding thepower from the secondary cell 12 to the fuel unit through the powersupply lines (+ and −) shown in FIG. 10 before the power ON sequence.

It is not preferable to directly connect the capacitor to the outputline of the fuel cell assembly and start the power ON sequence after thepower supply voltage sufficiently rises. This is because after the powersupply voltage sufficiently rises, the output current of the fuel cellassembly considerably decreases, as shown in FIG. 11. As is known, untilthe output current of the fuel cell assembly rises, a very long time isrequired as compared to other cells.

In this embodiment, as shown in FIGS. 12 and 13, the capacitor 18 isactively charged using a charge pump circuit 11 b through a diode 11 cunder the control of the power supply microcomputer. The charge pumpcircuit 11 b has a function of boosting the low-level voltage from thefuel cell assembly 2.

The power supply microcomputer monitors the state of charges in the fuelcell assembly and electric double-layered capacitor 18, and when thefuel cell assembly is set on the operative state, turns on the notebookpersonal computer and executes a power ON sequence 47 of the notebookpersonal computer 1.

More specifically, referring to FIG. 12, a control signal is output to aswitching transistor 11 a to turn on the switching transistor 11 a.Simultaneously, the operation of the charge pump circuit 11 b isstopped. Thus, the output from the fuel cell assembly is supplied to thenotebook personal computer 1.

In the process of activating the notebook personal computer 1, or duringthe operation of the notebook personal computer 1, the internal harddisk drive 19 is activated. At this time, since the motor of the harddisk drive is activated, a large rush current flows. The electricdouble-layered capacitor 18 also has a function of preventing such anabrupt variation in load from being directly transmitted to the fuelcell assembly, as shown FIG. 13.

If the influence of some system-side load on the fuel cell assembly 2 isallowable, the power supply section 11 having the arrangement shown inFIG. 14 may be used. In this case, the capacitor 18 is charged by thecharge pump circuit 11 b, and when the output from the fuel cellassembly 2 and the like reach predetermined values, switchingtransistors 11 e and 11 f are turned on.

Referring back to FIG. 9, although the power ON sequence 47 is the sameas the conventional power ON sequence 41, the number of components to bepowered on is smaller because the power consumption and function arereduced.

The subsequent sequence in the fuel cell assembly mode is almost thesame as that in the normal mode, and a detailed description thereof willbe omitted. A frame 51 shown in FIG. 9 represents the fuel cell assemblymode. When the notebook personal computer 1 is executing certainoperation, mode transit is not allowed.

When the notebook personal computer 1 is powered off and set in thestate 45, the mode can be changed. Similarly, in the normal mode, i.e.,in the state represented by the frame 44, transit to the fuel cellassembly mode is not allowed.

In the normal mode, the power input terminal 17 from the fuel cellassembly is disconnected by the switch in the power supply section 11.Hence, even when the user connects the fuel cell assembly while thenotebook personal computer 1 is being operated by, e.g., cell drive, thefuel cell assembly is actually kept disconnected. After the user powersoff a node PC, the notebook personal computer can transit to the fuelcell assembly mode through the neutral mode.

In the state 45 in which the node PC is OFF although the fuel cellassembly is connected, when, e.g., the Wake On LAN condition issatisfied, the notebook personal computer operates as if the conditionwere satisfied in the neutral mode.

That is, the notebook personal computer 1 is activated using the cell asthe power supply, and Wake ON LAN processing is started. Since thenormal mode is set at this time, the power from the fuel cell assemblyis disconnected from the notebook personal computer 1, as describedabove.

According to the notebook personal computer system of this embodiment,in addition to the effect of the computer system of the firstembodiment, since the capacitor is charged using the fuel cell assemblyuntil the output of the fuel cell assembly stabilizes, the energy lossin the entire system becomes small. In addition, since the capacitor isnot directly connected to the system, an excess rush current can beprevented from flowing to the fuel cell assembly.

As has been described above in detail, according to the presentinvention, a computer system in which water produced from the fuel cellassembly is prevented from entering the computer can be provided. Inaddition, a computer system which can normally operate using even a fuelcell assembly for which both the output power and output voltage are lowcan be provided.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A computer system including a computer and a fuel cell thatcommunicates with the computer and supplies power to the computer, thecomputer comprising: a power supply switch configured to instruct thecomputer to activate; a notification unit configured to cause thecomputer to notify the fuel cell to start operating, when the computeris instructed by the power switch to activate; a unit configured todetermine whether or not an output value of the fuel cell is greaterthan a predetermined output value, after the fuel cell is activatedbased on a notification output by the notification unit; and a unitconfigured to start an activation process of the computer when theoutput value of the fuel cell is determined to be greater than thepredetermined value.
 2. A computer system according to claim 1, whereinthe fuel cell starts to activate based on a notification output by thenotification unit.
 3. A computer system according to claim 1, whereinthe chemical reaction in the fuel cell starts based on a notificationoutput by the notification unit.
 4. A computer system according to claim1, wherein the computer further comprises a unit configured to supplypower to the fuel cell after the notification unit outputs anotification.
 5. A computer system according to claim 1, wherein thecomputer further comprises: a secondary battery capable ofcharging/discharging; and a unit configured to supply power from thesecondary battery to the fuel cell.
 6. A computer system according toclaim 1, wherein the computer further comprises: a condenser for storingpower generated by the fuel cell, when it is determined that the outputvalue of the fuel cell is not greater than the predetermined outputvalue; and a unit configured to switch a power supply from the fuel cellbetween the condenser and a main board of the computer based on theoutput value from the fuel cell.
 7. In a computer system including acomputer and a fuel cell that communicates with the computer andsupplies power to the computer, wherein the computer includes a powersupply switch capable of instructing the computer to activate, anactivation method comprising: causing the computer to notify the fuelcell to start operating, when the computer is instructed by the powersupply switch to activate; determining whether or not an output value ofthe fuel cell is greater than a predetermined output value, after thefuel cell is activated based on an instruction output by the powersupply switch; and starting an activation process of the computer whenthe output value of the fuel cell is determined to be greater than thepredetermined output value.
 8. An activation method according to claim7, wherein the fuel cell starts to activate based on the notificationfrom the computer.
 9. An activation method according to claim 7, whereina chemical reaction starts in the fuel cell based on the notificationfrom the computer.
 10. An activation method according to claim 7,wherein the computer supplies power to the fuel cell after the computernotifies the fuel cell to start operating.
 11. An activation methodaccording to claim 7, wherein the computer further comprises a secondarybattery capable of charging/discharging, the method further comprisingsupplying power from the secondary battery to the fuel cell before thecomputer is activated.